Charge-transfer effect on local lattice distortion in a HfNbTiZr high entropy alloy

TL;DR

This study reveals that charge transfer among atoms with different electronegativities plays a crucial role in stabilizing highly distorted high-entropy alloys, challenging the traditional hard sphere model and informing alloy design.

Contribution

It demonstrates that charge transfer effects significantly influence local lattice distortion in HEAs, providing new insights beyond the hard sphere approximation.

Findings

Charge transfer reduces atomic-size mismatch in HEAs.

Charge transfer competes with local lattice distortion effects.

Findings aid in designing stable, severely distorted HEAs.

Abstract

It is often assumed that atoms are hard spheres in the estimation of local lattice distortion (LLD) in high-entropy alloys (HEAs). However, our study demonstrates that the hard sphere model misses the key effect, charge transfer among atoms with different electronegativities, in the understanding of the stabilization of severely-distorted HEAs. Through the characterization and simulations of the local structure of the HfNbTiZr HEA, we found that the charge transfer effect competes with LLD to significantly reduce the average atomic-size mismatch. Our finding may form the basis for the design of severely distorted, but stable HEAs.